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wvspeedfreak
02-22-2005, 07:05 PM
What should the compression be on a fresh ct 350 prox powervalve engine?What is the proper procedure for checking it?I held the throttle wide open and kicked it over 3 times and I can only get 145psi out of it.This seems kind of low to me what do you think?
ESR350r
02-22-2005, 07:46 PM
That seems alittle low, my 330 was 155 after running 2 cross country races and hill climbing. Sounds like you checked it right. you might want to kick it a few more times. Kick it until it maxes out, that and try it after it is warmed up. It will be lower when it is cold just because things have not expanded. I hope this helps.
wvspeedfreak
02-22-2005, 07:53 PM
Thanks for your input.It seems to me that maybe the larger bores might not have as much compression as say a stock size bore due to the larger combustion area.I don't know:confused:
ESR350r
02-22-2005, 08:52 PM
I am not sure about the big bore having lower compression because I ride with a guy on a 420 banshee that has over 200. Alot of it depends on the dome you have in your head. I think my 330 storker was 175+ when i first got it. Running it hard and hot really dropped my compression.
wilkin250r
02-23-2005, 10:58 AM
Throttle wide open, and kick it until the guage stops moving. I may be more than 3 kicks.

145 is really low, even for a drag-ported engine. 165 would be the bare minumum, and it SHOULD be higher than that. I would estimate you should see at least 180, and even more if you've got a low or mid-range port.
zedicus00
02-23-2005, 02:25 PM
i hav 185 on my drag ported pump gas running 246R (stockbore). but yes 145 is low on anybore. kick it hard about 5 times.
wvspeedfreak
02-23-2005, 06:47 PM
Well,I talked to Allen Knowles at CT today and he said with the dome I have it should be 200 psi.I guess I will be pulling the top end to see what is going on in there.
wvspeedfreak
03-01-2005, 02:27 PM
I pulled the head off today and the piston is way loose in the bore so now I need to have it bored and a new piston put in.I am trying to figure out if this engine has been bored before.There are no markings on the top of the piston indicating an overbore.Is there any other way to tell?If I pull the cylinder off and take the piston all the way out would there be a part number on the piston anywhere letting me know if it is oversize or not?This has the CT 350 top end on it.